A Remote Direct Memory Access Protocol Specification
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From: The IESG <email@example.com> To: IETF-Announce <firstname.lastname@example.org> Cc: Internet Architecture Board <email@example.com>, RFC Editor <firstname.lastname@example.org>, rddp mailing list <email@example.com>, rddp chair <firstname.lastname@example.org> Subject: Protocol Action: 'Direct Data Placement over Reliable Transports' to Proposed Standard The IESG has approved the following documents: - 'Direct Data Placement over Reliable Transports ' <draft-ietf-rddp-ddp-08.txt> as a Proposed Standard - 'A Remote Direct Memory Access Protocol Specification ' <draft-ietf-rddp-rdmap-08.txt> as a Proposed Standard These documents are products of the Remote Direct Data Placement Working Group. The IESG contact persons are Lars Eggert and Magnus Westerlund. A URL of this Internet-Draft is: http://www.ietf.org/internet-drafts/draft-ietf-rddp-ddp-08.txt
Technical Summary Direct Data Placement Protocol (DDP) enables an Upper Layer Protocol (ULP) to send data to a Data Sink without requiring the Data Sink to Place the data in an intermediate buffer - thus when the data arrives at the Data Sink, the network interface can Place the data directly into the ULP's buffer. This can enable the Data Sink to consume substantially less memory bandwidth than a buffered model. Additionally, this can also enable the network protocol to consume substantially fewer CPU cycles than if the CPU was used to move the data, and removes the bandwidth limitation of only being able to move data as fast as the CPU can copy the data. DDP preserves ULP record boundaries (messages) while providing a variety of data transfer mechanisms and completion mechanisms to be used to transfer ULP messages. The Remote Direct Memory Access Protocol (RDMAP) operates over the Direct Data Placement Protocol (DDP). RDMAP provides read and write services directly to applications and enables data to be transferred directly into ULP Buffers without intermediate data copies. It also enables a kernel bypass implementation. Working Group Summary DDP provides two mechanisms, a Tagged Buffer mechanism for Remote DMA transfers where the network communication contains a destination memory offset, and an Untagged Buffer mechanism that supports socket-like sends where the receiver chooses the buffer on its own. The WG has strong consensus that both mechanisms are required in order for an implementation to exercise control over all memory buffer resources used for network communication. RDMAP supports both DMA (direct read/write to identified buffer) style and message (send, receiver selects buffer) style transfers. The WG has strong consensus that both transfer styles are required in order for an implementation to exercise control over all memory buffer resources used for network communication, and to appropriately support usage where a DMA style transfer is followed by a message style transfer whose reception is used to infer completion of the preceding DMA style transfer. Protocol Quality These protocols have been reviewed for the RDDP WG by David Black, who also acted as PROTO Shepherd. Francis Dupont (Francis.Dupont@point6.net) was the GEN-ART Reviewer for these documents. These protocols have been reviewed for the IESG by Lars Eggert and Jon Peterson. Note to RFC Editor Section 1 of draft-ietf-rddp-rdmap, last paragraph: this document are to be interpreted as described in [RFC2119]." ^ Note: remove the double-quote after the period. Section 10.1 of draft-ietf-rddp-rdmap: Remove the unused [VERBS] reference.